LED lighting technology is rapidly developing to replace traditional incandescent and fluorescent lightings. LED tube lamps are mercury-free in comparison with fluorescent tube lamps that need to be filled with inert gas and mercury. Thus, it is not surprising that LED tube lamps are becoming a highly desirable illumination option among different available lighting systems used in homes and workplaces, which used to be dominated by traditional lighting options such as compact fluorescent light bulbs (CFLs) and fluorescent tube lamps. Benefits of LED tube lamps include improved durability and longevity and far less energy consumption; therefore, when taking into account all factors, they would typically be considered as a cost effective lighting option.
Typical LED tube lamps have a variety of LED elements and driving circuits. The LED elements include LED chip-packaging elements, light diffusion elements, high efficient heat dissipating elements, light reflective boards and light diffusing boards. Heat generated by the LED elements and the driving elements is considerable and mainly dominates the illumination intensity such that the heat dissipation needs to be properly disposed to avoid rapid decrease of the luminance and the lifetime of the LED lamps. Problems including power loss, rapid light decay, and short lifetime due to poor heat dissipation are always the key factors in consideration of improving the performance of the LED illuminating system. It is therefore one of the important issues to solve the heat dissipation problem of the LED products.
Nowadays, most of the LED tube lamps use plastic tubes and metallic elements to dissipate heat from the LEDs. The metallic elements are usually exposed to the outside of the plastic tubes. This design improves heat dissipation but heightens the risk of electric shocks. The metallic elements may be disposed inside the plastic tubes, however the heat still remains inside the plastic tubes and deforms the plastic tubes. Deformation of the plastic tubes also occurs even when the elements to dissipate heat from the LEDs are not metallic.
The metallic elements disposed to dissipate heat from the LEDs may be made of aluminum. However, aluminum is too soft to sufficiently support the plastic tubes when the deformation of plastic tubes occurs due to the heat as far as the metallic elements disposed inside the plastic tubes are concerned.
As a result, the current related skills still could not be applied to deal with the above-mentioned worse heat conduction, poor heat dissipation, heat deformation, and electric shock defects. On the other hand, the LED tube lamp may be provided with power via two ends of the lamp and a user is easily to be electric shocked when one end of the lamp is already inserted into an terminal of a power supply while the other end is held by the user to reach the other terminal of the power supply. In view of these issues, the claimed invention and the preferred embodiments are proposed below.